Overview

Though the Celtic world at its apex covered much of western and central Europe, it was not politically unified nor was there any substantial central source of cultural influence or homogeneity; as a result, there was a great deal of variation in local practices of Celtic religion (although certain motifs—for example, the god Lugh—appear to have diffused throughout the Celtic world). Inscriptions to more than three hundred deities, often equated with their Roman counterparts, have survived, but of these most appear to have been genii locorum, local or tribal gods, and few were widely worshipped. However, from what has survived of Celtic mythology, it is possible to discern commonalities which hint at a more unified pantheon than is often given credit.

The nature and functions of these ancient gods can be deduced from their names, the location of their inscriptions, their iconography, the Roman gods they are equated with, and similar figures from later bodies of Celtic mythology.

Celtic mythology is found in a number of distinct, if related, subgroups, largely corresponding to the branches of the Celtic languages:

Historical sources

Because of the scarcity of surviving materials bearing written Gaulish, it is surmised that the pagan Celts were not widely literate— although a written form of Gaulish using the Greek, Latin and North Italic alphabets was used (as evidenced by votive items bearing inscriptions in Gaulish and the Coligny Calendar). Caesar attests to the literacy of the Gauls, but also wrote that their priests, the druids, were forbidden to use writing to record certain verses of religious significance (Caesar, De Bello Gallico 6.14) while also noting that the Helvetii had a written census (Caesar, De Bello Gallico 1.29).

Rome introduced a more widespread habit of public inscriptions, and broke the power of the druids in the areas it conquered; in fact, most inscriptions to deities discovered in Gaul (modern France and Northern Italy), Britain and other formerly (or presently) Celtic-speaking areas post-date the Roman conquest.

And although early Gaels in Ireland and parts of modern Wales used the Ogham script to record short inscriptions (largely personal names), more sophisticated literacy was not introduced to Celtic areas that had not been conquered by Rome until the advent of Christianity; indeed, many Gaelic myths were first recorded by Christian monks, albeit without most of their original religious meanings.

The mythology of Ireland

The oldest body of myths is found in early medievalmanuscripts from Ireland. These were written by Christians, so the formerly divine nature of the characters is obscured. The basic myth appears to be a war between two apparently divine races, the Tuatha Dé Danann and the Fomorians, which forms the basis for the text Cath Maige Tuireadh (the Battle of Mag Tuireadh), as well as portions of the history-focused Lebor Gabála Érenn (the Book of Invasions). The Tuatha Dé represent the functions of human society such as kingship, crafts and war, while the Fomorians represent chaos and wild nature.

The Dagda

The supreme god of the Irish pantheon appears to have been The Dagda. The name means the 'Good God', not good in a moral sense, but good at everything, or all-powerful. The Dagda is a father-figure, a protector of the tribe and the basic Celtic god of whom other male Celtic deities were variants. Celtic gods were largely unspecialised entities, and perhaps more like a clan rather than as a formal pantheon.

Because the particular character of Dagda is a figure of burlesque lampoonery in Irish mythology, some authors conclude that he was trusted to be benevolent enough to tolerate a joke at his expense.

Irish tales depict the Dagda as a figure of power, armed with a spear and associated with a cauldron. In Dorset there is a famous outline of an ithyphallic giant known as the Cerne Abbas Giant with a club cut into the chalky soil. While this was probably produced in relatively modern times (English Civil War era), it was long thought to be a representation of the Dagda. This has been called into question by recent studies which show that there may have been a representation of what looks like a large drapery hanging from the horizontal arm of the figure, leading to suspicion that this figure actually represents Hercules (Heracles), with the skin of the Nemean Lion over his arm and carrying the club he used to kill it. In Gaul, it is speculated that the Dagda is associated with Sucellos, the striker, equipped with a hammer and cup.

The Morrígan

The Morrígan was a tripartite battle goddess of the ancient Irish Celts. Collectively she was known as the Morrígan, but her divisions were also referred to as Nemhain, Macha, and Badb (among other, less common names), with each representing different aspects of combat. She is most commonly known for her involvement in the Táin Bó Cúailnge, where she is at various times a helper and a hindrance to the hero Cúchulainn, and in the Cath Maige Tuireadh (the Battle of Mag Tuired) where she also plays the role of a poet, magician and sovereignty figure, and gives the victory to the Tuatha Dé Danann. She was most often represented as a crow or raven but could take many different forms, including a cow, wolf or eel. The Morrígan can be compared to other Indo-European goddesses of death such as Kali in the Hindu pantheon and the Valkyries in Norse Mythology.

Lúgh/Lug

The widespread diffusion of the god Lugus (seemingly related to the mythological figure Lugh in Irish) in Celtic religion is apparent from the number of place names in which his name appears, occurring across the Celtic world from Ireland to Gaul. The most famous of these are the cities of Lugdunum (the modern French city of Lyon) and Lugdunum Batavorum (the modern city of Katwijk, 10 kilometers to the west of Leiden). Lug is described in the Celtic myths as a latecomer to the list of deities, and is usually described as having the appearance of a young man. He is often associated with light, the sun, and summer. His weapons were the throwing-spear and sling, and in Ireland a festival called the Lughnasa (Modern Irish lúnasa) was held in his honour.

Others

Among these are the goddess Brigid (or Brigit), the Dagda's daughter; nature goddesses like Tailtiu and Macha; Epona, the horse goddess; and Ériu.
Male gods included Goibniu, the smith god and immortal brewer of beer, as well as Angus Og, the god of love.

The mythology of Wales

Less is known about the pre-Christian mythologies of Britain than those of Ireland. Important reflexes of British mythology appear in the Four Branches of The Mabinogi, especially in the names of several characters, such as Rhiannon (‘the Divine Queen’), Teyrnon (‘the Divine King’), and Bendigeidfran (‘Bran [Crow] the Blessed’). Other characters, in all likelihood, derive from mythological sources, and various episodes, such as the appearance of Arawn, a king of the Otherworld seeking the aid of a mortal in his own feuds, and the tale of the hero who cannot be killed except under seemingly contradictory circumstances, can be traced throughout Indo-European myth and legend. The children of Llŷr (‘Sea’ = Irish Lir) in the Second and Third Branches, and the children of Dôn (Danu in Irish and earlier Indo-European tradition) in the Fourth Branch are major figures, but the tales themselves are not primary mythology.

While further mythological names and references appear elsewhere in Welsh narrative and tradition, especially in the tale of Culhwch and Olwen, where we find, for example, Mabon ap Modron (‘the Divine Son of the Divine Mother’), and in the collected Triads of the Island of Britain, not enough is known of the British mythological background to reconstruct either a narrative of creation or a coherent pantheon of British deities. Indeed, though there is much in common with Irish myth, there may have been no unified British mythological tradition per se. Whatever its ultimate origins, the surviving material has been put to good use in the service of literary masterpieces that address the cultural concerns of Wales in the early and later Middle Ages.

Remnants of Gaulish and other mythology

The Celts also worshipped a number of deities of which we know little more than their names. Classical writers preserve a few fragments of legends or myths that may possibly be Celtic.

According to the Syrian rhetorician Lucian, Ogmios was supposed to lead a band of men chained by their ears to his tongue as a symbol of the strength of his eloquence.

The Roman poet Lucan (1st century AD) mentions the gods Taranis, Teutates and Esus, but there is little Celtic evidence that these were important deities.

Along with dedications giving us god names, there are also deity representations to which no name has yet been attached. Among these are images of a three headed or three faced god, a squatting god, a god with a snake, a god with a wheel, and a horseman with a kneeling giant. Some of these images can be found in Late Bronze Agepeat bogs in Britain, indicating the symbols were both pre-Roman and widely spread across Celtic culture. The distribution of some of the images has been mapped and shows a pattern of central concentration of an image along with a wide scatter indicating these images were most likely attached to specific tribes and were distributed from some central point of tribal concentration outward along lines of trade. The image of the three headed god has a central concentration among the Belgae, between the Oise, Marne and Moselle rivers. The horseman with kneeling giant is centered on either side of the Rhine. These examples seem to indicate regional preferences of a common image stock.

Julius Caesar’s comments on Celtic religion and their significance

The classic entry about the Celtic gods of Gaul is the section in Julius Caesar's Commentarii de bello Gallico (52–51 BC; The Gallic War). In this he names the five principal gods worshipped in Gaul (according to the practice of his time, he gives the names of the closest equivalent Roman gods) and describes their roles. Mercury was the most venerated of all the deities and numerous representations of him were to be discovered. Mercury was seen as the originator of all the arts (and is often taken to refer to Lugus for this reason), the supporter of adventurers and of traders, and the mightiest power concerning trade and profit. Next the Gauls revered Apollo, Mars, Jupiter, and Minerva. Among these divinities the Celts are described as holding roughly equal views as did other populations: Apollo dispels sickness, Minerva encourages skills, Jupiter governs the skies, and Mars influences warfare. In addition to these five, he mentions that the Gauls traced their ancestry to Dis Pater.

The problem with Caesar’s ‘equivalent’ Roman gods

As typical of himself as a Roman of the day, though, Caesar does not write of these gods by their Celtic names but by the names of the Roman gods with which he equated them, a process that significantly confuses the chore of identifying these Gaulish gods with their native names in the insular mythologies. He also portrays a tidy schema which equates deity and role in a manner that is quite unfamiliar to the colloquial literature handed down. Still, despite the restrictions, his short list is a helpful and fundamentally precise observation. In balancing his description with the oral tradition, or even with the Gaulish iconography, one is apt to recollect the distinct milieus and roles of these gods. Caesar's remarks and the iconography allude to rather dissimilar phases in the history of Gaulish religion. The iconography of Roman times is part of a setting of great social and political developments, and the religion it depicts may actually have been less obviously ordered than that upheld by the druids (the priestly order) in the era of Gaulish autonomy from Rome. Conversely, the want of order is often more ostensible than factual. It has, for example, been noticed that out of the several hundred names including a Celtic aspect that can be found in Gaul the greater part crop up only once. This has led some scholars to conclude that the Celtic deities and the related cults were local and tribal as opposed to pan-Celtic. Proponents of this opinion quote Lucan's reference to a divinity called Teutates, which they translate as “tribal spirit” (*teuta is believed to have meant “tribe” in Proto-Celtic). The apparent array of divine names may, nonetheless, be justified differently: many may be mere epithets applied to key gods worshiped in extensive pan-Celtic cults. The concept of the Celtic pantheon as a large number of local deities is gainsaid by certain well-testified gods whose cults seem to have been followed across the Celtic world.